Digital watermarking involves a process of modifying physical or electronic content to embed a machine-readable code, customer information or logo images into object content, particularly for information security and data access authentication purposes. The content may be modified such that the embedded code is imperceptible or inaudible to the user, yet may be detected or extracted through a detection or extraction process. Most commonly, digital watermarking is applied to media signals including images, audio signals, and video signals. However, it may also be applied to other types of media objects, including documents (for instance, through line, word or character shifting), software, multi-dimensional graphics models, and surface textures of objects.
Digital watermarking systems typically have two primary components: an encoder that embeds the watermark in a host content signal, and a decoder that detects or extracts and reads the embedded watermark from a signal suspected of containing a watermark (a suspect signal). The encoder embeds a watermark by altering the host content signal. Typically, random sequences or customer logo images are used as keys to watermark media signals to be used as a watermark during the embedding process.
The decoder analyzes a suspect signal to detect whether a watermark is present to extract a watermark. The watermark can only be detected in the suspect signal by comparing exactness or near exactness of the embedded watermark. The pirates of content may try to eliminate the watermark from the media content by manipulating media signals including audio, video, image, computer readable medium, Compact Disc (CD), hard disk, Floppy drive, and any kind of document and the like.
Hence, a need for a watermark detection technique is felt particularly for commercially distributed content including audio, video and gaming to ascertain type, strength and coverage of manipulation and location of the attack in the content.
Also, there exists a need to have a robust method and system for embedding and detecting or extracting the watermark in the electronic content for each of the possible attacks and combinations thereof, wherein the electronic media goes through various kinds of intentional distortions, unintentional distortions, signal processing and cryptographic attacks and other combinations of the attacks which are unknown while detecting the watermarks.
Moreover, the present-day watermark detection techniques either require the original content file or some of its processed parameters to detect the watermark embedded in the digital content. Therefore, there is also felt a need for a watermarking technique which can perform watermark detection without requiring the original content file or its processed parameters.